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1. Field of the Invention
The present invention relates to graphics editors, and more particularly to graphics editors for constructing and editing complex graphics images, and to methods for forming and editing complex graphics images through the use of a user interface.
2. Description of Related Art
The standard What-You-See-Is-What-You-Get (WYSIWYG) point-and-click editing paradigm presents difficulties for the construction of complex graphics images. If the user can only view the final WYSIWYG image, it is hard to see and understand its composition, that is, its components and their relations. Consequently, it is difficult to point to the components and modify them. It is also difficult to reuse the same image, whether transformed or modified, without interactively copying it one or more times.
For example, to operate on a graphics image, users need to indicate--that is, refer to--the part or parts of the image they wish to effect. This is often done by pointing with a mouse. Experienced users know that when manipulating complex images, it can be difficult to find and point to the relevant parts, especially when there are dense clusters of overlapping figures. Related to this, users sometimes find that parts of the image they can see are not recognized by the editor, so cannot be pointed at and operated on independently. A simple example is when a rectangle is created using a "rectangle" tool. It typically is not possible to select one of the sides of the rectangle and move it away. To do this, the rectangle must be created as four line segments. There is no ability to reparse or reregister the rectangle--to decompose it into parts other than the ones out of which it was first constructed. This ability to reregister is closely related to the problem of reference, since, the registration of an image determines the parts that can be referred to.
Another problem which arises with the WYSIWYG display screen is the inability of an operator to determine the graphical domain in which a portion of a complex image is located. A number of commercially available text/graphics editors are capable of constructing images in both the bitmap and vector domains. For example, Superpaint.RTM. is a graphics editor which incorporates some painting (bitmap) and drawing (vector) capabilities. However, unless the user of the system knows (based on experience) in which domain a particular portion of an image is created, the user may attempt to perform editing operations on that image portion while in a domain in which that editing cannot be performed.
Accordingly, a need exists for a graphics editor which conveys the underlying components and operations which are performed to produce a complex image to the operator, and which permits the operator to easily construct and edit complex images.
U.S. Pat. No. 4,901,063 to Kimura et al discloses an image processing apparatus which displays both a sample image as it appears before a selected image process is executed, and a processed sample image corresponding to an image resulting from the selected image process. With the apparatus, an operator can obtain processed sample images and can perform image processing on an original image by inputting a processing command.
U.S. Pat. No. 4,611,306 to Crehan et al discloses a word processing system having a display menu/chart key for toggling back and forth between a graphics image and a menu display used to define a graphics image. The system provides an interface which allows an operator to visually check and revise the definition of a graphics image. By using the menu/chart key, the operator can see how changing a menu item will cause a graphics image to be changed. When the key is pressed while a graphic image is being displayed, a most recently processed menu is again displayed. This editing system does not permit the viewing of an entire complex image formation process, or the simultaneous viewing of an image formation process and the image formed thereby.
U.S. Pat. No. 4,928,247 to Doyle et al discloses a host system which executes one or more application programs which result in graphics data structures. These graphics data structures are then continuously and asynchronously traversed. In particular, hierarchical data structures are built in memory to permit the definition of complex data structures representative of the primitives, attributes and geometric transformations of three dimensional objects. This data structure is then asynchronously traversed by a structure walker.
U.S. Pat. No. 4,021,976 to Wexelblat et al discloses a method and system for generating dynamic interactive visual representations of complex information structures within a computer. Boundaries of the information system are established, and a set of mathematical relationships is provided which indicates a degree of correlation between parameters of interest to a user and segments of information contained within the boundaries. A visual display is generated for the user which has a plurality of iconic representations and features corresponding to the parameters defined by the mathematical relationships. The iconic representations and visual features of the visual display change with movement of the mathematical relationships within the boundaries of the information system according to the degree of correlation between parameters of interest and a segment of information through which the mathematical relationships are passing. The shapes of the icons can be used to denote the type of data represented by the icons.
U.S. Pat. No. 4,860,204 to Gendron et al discloses a method for constructing computer programs through use of visual graphical representations. Computer programs are illustrated as visual roadmaps of an intended sequence of actions. Each operational entity of a program graph displayed on a screen is represented as an elemental unit. The elemental unit is a multidimensional graphical unit of programming information which has four modes, or "layers" of operation. The elemental units reside in very general form in a work station library and are optimized by specialization. The system of Gendron et al permits programs to be written using icons instead of by writing source code.
U.S. Pat. No. 4,953,106 to Gansner et al discloses a computer implemented technique for drawing directed graphs providing reduced crossing and improved picture quality.